interface Com{
    int add(int a ,int b);
}
abstract class A{
    abstract int add (int a,int b);
}
class B extends A implements Com{
    public int add (int a,int b){
        return a+b;
    }
}
public class E2 {
    public static void main (String args[]){
        B b=new B();
        Com com=b;
        System.out.println(com.add(12,6));
        A a=b;
        System.out.println(a.add(10,5));
    }
}
